---
title: Add last modified time
description: Build a remark plugin to add the last modified time to your Markdown and MDX.
i18nReady: true
type: recipe
---

import PackageManagerTabs from '~/components/tabs/PackageManagerTabs.astro'

Learn how to build a [remark plugin](https://github.com/remarkjs/remark) that adds the last modified time to the frontmatter of your Markdown and MDX files. Use this property to  display the modified time in your pages.

## Recipe

1. Install Helper Packages

   Install [`Day.js`](https://www.npmjs.com/package/dayjs) to modify and format times:

   <PackageManagerTabs>
     <Fragment slot="npm">
       ```shell
       npm install dayjs
       ```
     </Fragment>
     <Fragment slot="pnpm">
       ```shell
       pnpm add dayjs
       ```
     </Fragment>
     <Fragment slot="yarn">
       ```shell
       yarn add dayjs
       ```
     </Fragment>
   </PackageManagerTabs>

2. Create a Remark Plugin

   This plugin uses `execSync` to run a Git command that returns the timestamp of the latest commit in ISO 8601 format. The timestamp is then added to the frontmatter of the file.

     ```js title="remark-modified-time.mjs"
     import { execSync } from "child_process";

     export function remarkModifiedTime() {
       return function (tree, file) {
         const filepath = file.history[0];
         const result = execSync(`git log -1 --pretty="format:%cI" "${filepath}"`);
         file.data.astro.frontmatter.lastModified = result.toString();
       };
     }
     ```
		<details>
		<summary>Using the file system instead of Git</summary>

		 Although using Git is the recommended way to get the last modified timestamp from a file, it is possible to use the file system modified time.
     This plugin uses `statSync` to get the `mtime` (modified time) of the file in ISO 8601 format. The timestamp is then added to the frontmatter of the file.
     
     ```js title="remark-modified-time.mjs"
     import { statSync } from "fs";

     export function remarkModifiedTime() {
       return function (tree, file) {
         const filepath = file.history[0];
         const result = statSync(filepath);
         file.data.astro.frontmatter.lastModified = result.mtime.toISOString();
       };
     }
     ```
		</details>

3. Add the plugin to your config

   ```js title="astro.config.mjs"
   import { defineConfig } from 'astro/config';
   import { remarkModifiedTime } from './remark-modified-time.mjs';

   export default defineConfig({
     markdown: {
       remarkPlugins: [remarkModifiedTime],
     },
   });
   ```

   Now all Markdown documents will have a `lastModified` property in their frontmatter.

4. Display Last Modified Time

   If your content is stored in a [content collection](/en/guides/content-collections/), access the `remarkPluginFrontmatter` from the `entry.render()` function. Then render `lastModified` in your template wherever you would like it to appear.

   ```astro title="src/pages/posts/[slug].astro" {3-4,6,17,19-21,28}
   ---
   import { CollectionEntry, getCollection } from 'astro:content';
   import dayjs from "dayjs";
   import utc from "dayjs/plugin/utc";

   dayjs.extend(utc);

   export async function getStaticPaths() {
     const blog = await getCollection('blog');
     return blog.map(entry => ({
       params: { slug: entry.slug },
       props: { entry },
     }));
   }

   const { entry } = Astro.props;
   const { Content, remarkPluginFrontmatter } = await entry.render();

   const lastModified = dayjs(remarkPluginFrontmatter.lastModified)
     .utc()
     .format("HH:mm:ss DD MMMM YYYY UTC");
   ---

   <html>
     <head>...</head>
     <body>
       ...
       <p>Last Modified: {lastModified}</p>
       ...
     </body>
   </html>
   ```

   If you're using a [Markdown layout](/en/guides/markdown-content/#markdown-and-mdx-pages), use the `lastModified` frontmatter property from `Astro.props` in your layout template.

   ```astro title="src/layouts/BlogLayout.astro" {2-3,5,7-9,15}
   ---
   import dayjs from "dayjs";
   import utc from "dayjs/plugin/utc";

   dayjs.extend(utc);

   const lastModified = dayjs()
     .utc(Astro.props.frontmatter.lastModified)
     .format("HH:mm:ss DD MMMM YYYY UTC");
   ---

   <html>
     <head>...</head>
     <body>
       <p>{lastModified}</p>
       <slot />
     </body>
   </html>
   ```
